The invention relates to a conveying device comprising a direction changing band for vertically positioning ferromagnetic can bodies (hereinafter referred to as cans) which are discharged from a unit in a horizontal position onto an upright can carrying band.
During welding of their longitudinal seam, rounded can bodies are "horizontally" guided past a welding unit, i.e., their axis is horizontally aligned with the direction of transport as disclosed in, for example, European Application No. EP-A2-0,420,018. Accordingly, the welded can body leaves the drying path of the welding machine horizontally on a transport unit.
To feed the can bodies into processing units, such as edge-forming machines, they are usually fed upright, i.e., with their longitudinal axis vertically aligned. Accordingly, these can bodies must be transferred from a horizontal to an upright position.
It is known how to convey can bodies to a transfer and direction changing band which, because it operated at a greater rotational speed in relation to the forward speed of the feeding unit, is often referred to in the prior art as an acceleration band. Due to the increased speed, the cans on the acceleration band are spaced at a greater distance from one another. From the acceleration band, the cans are discharged to a further band, a so-called upright can carrying band. The upper band portion of the acceleration band runs over a large direction changing wheel. The direction of transport, and consequently, the axis of the cans is thus deflected downwardly by 45.degree. to 90.degree..
The transfer or further transport of the cans by means of the upright can carrying band occurs in relation to the discharging portion of the acceleration band essentially at less than 90.degree., i.e., the upper portion of the upright can carrying band is correspondingly inclined in the transfer region at an angle up to 45.degree.. The upper band portion of the upright can carrying band thus inclined is guided around a direction changing roll and changed to a horizontal orientation upon reaching a desired height so that the cans are in a vertical position during their transfer to a processing unit.
In order for the cans to be moved from the acceleration band to the upright can carrying band, the mutual distance of the cans on the acceleration band and, correspondingly, the rotational speed of the acceleration band must be sufficiently high. At welding speeds of 1.7 m/s, the rotational speed of the acceleration band would have to be up to 3.3 m/s, depending on the length of the can bodies. However, if the cans are long, speeds like this result in significant problems. With a certain length of can bodies, the high rotational speed results in the cans being lifted off the acceleration band due to centrifugal forces exerted during direction changing, especially since the outer surface of the can bodies theoretically contacts the direction changing wheel at the belt band only at one point. Furthermore, the high impact speed can cause damage to the edges of the open can bodies, and the sharp edges can also cause extensive wear of the receiving upright can carrying band. Moreover, the safety of the cans, especially in an inclined position during transfer by the upright can carrying band is also jeopardized due to gravitational and acceleration forces.